Windows 10 users connecting to a WTI device USB port will automatically have a serial driver installed. Refer here for more information.
Windows 7 users have to do a few more steps to be able to talk over USB
First you need the Gadget Serial v2.4 Windows definition file, located here: linux-cdc-acm.inf, unzip the file and store it someplace.
In Windows 7 run the Device Manager:
devmgmt.msc at a Windows command prompt.
Find the Other devices where the Gadget Serial v2.4 device is displayed:
Device Manager, no Gadget Serial v2.4 driver install.
Click on the right mouse button and from the popup menu select Update Driver Software...
Device Manager, Update Driver Software
Choose Browse my computer for driver software and choose the location of the linux-cdc-acm.inf file downloaded and uncompressed previously.
Device Manager, Browse my computer
Wait for the driver to configure, you may get a Windows warning about the driver not being signed, but the driver is only a configuration file telling Windows how to use the drivers that are already installed on your Windows machine.
Device Manager, Installing driver software
After the Driver had finished, The Device Manager should refresh listing the Gadget Serial under the heading Ports (COM & LPT)
Device Manager, Gadget Serial v2.4 driver installed.
Now you can use you favorite terminal program on the serial port assigned to this driver to talk to your WTI device.